Monitoring PV for public education [RE-wrenches]

[John Raynes]

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Drake and all,

Thought I'd chip in here.  Have any of you considered using data loggers 
for doing this work?  They're designed to sit by themselves for weeks or 
months at a time, using almost no power, and storing all the data until you 
can get around to hooking up a computer to download the data.  I find them 
a lot cleaner to work with than setting up a system that requires 
connection to a computer at all times in order to collect data.  Computers 
crash regularly as we all know, and they also present a serious power 
burden if you're not grid tied.

The Schott kiosk systems use Campbell Scientific CR10X data loggers (at 
least they used to).  And yes, they still are expensive relative to overall 
RE system cost, unless you're talking about a commercial-sized 
install.  Campbell recently came out with a lower priced logger, still 
suitable for the kinds of systems most of you are describing.  The cost of 
the loggers is now down to the point that the bulk of the system cost for 
monitoring is in the sensors and transducers themselves, and the computer 
links.  It just adds up by the time you add sensors for wind speed, solar 
rad, temperature w/shield, and a few DC current sensors and an AC watt 
transducer or two.  (And the mounting, wiring, small protective enclosure, 
etc, etc.)

Disclosure: I run my own wrench business, but installing and programing RE 
data logging systems has been my main niche in solar so far.  (Surviving on 
wrenching alone in Utah is tough going or else I'm really doing something 
wrong.)   Contact me off list and I'd be happy to chat further on RE 
monitoring with anyone interested.  I have implemented systems for doing 
array monitoring of up to a few dozen PV strings at a fairly reasonable 
cost, and I can probably help point you in a good direction.

John Raynes
Principal Engineer
Raynes Engineering, Inc./RE Solar
Logan, UT

Phone:  801-569-2400
email:          john at raynes.com
Web site:       www.raynes.com



At 04:09 PM 9/29/02 -0600, you wrote:
>Hi Ian and Graham,
>
>The equipment I've found is much less expensive.  It is mainly the highly 
>versatile equipment from B & B Electronics. If you can generate a signal, 
>it should be possible to put it into a form that the device can 
>automatically send through a modem.
>
>Initially I found only highly expensive equipment to do the job, such as 
>the excellent and very pricey equipment from Keithley Instruments. .  What 
>I'm interested in testing is the amperage, voltage, and temperature of 
>wiring on PV arrays.  This is part of the RE Lab project (The Renewable 
>Power Installers Advocacy Program), which is a part of IPP, which we are 
>now seeking funding for.
>
>The system is built around the B & B Electronics Caddy DCDSS1 Data 
>Transmission Unit.  It took a bit of research to figure out how to use to 
>with various transducers.  This unit sells for $349.95.  Also needed is an 
>analog input module for $279.95.  There are some other components needed 
>as well, including the various transducers.
>
>I'm sure it would be possible to take the signal from an anemometer, or 
>use the output of a photo cell to generate data that would be 
>acceptable.  I'd be very interested in setting up monitoring systems to do 
>these tasks.
>
>Best,
>
>Drake
>

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